Effect of Nanoparticle Additives on Spray Dynamics in a Pressure-Swirl Atomizer: A Numerical Study

Abstract This study numerically investigates the influence of nanoparticle additives on the spray characteristics of liquid fuels within a pressure-swirl atomizer. A Lagrangian-based approach coupled with the Discrete Phase Model (DPM) was employed in ANSYS Fluent to model transient multiphase nanofluid flow. Fischer-Tropsch (FT) and RP-3 fuels were mixed with aluminum (Al) and aluminum oxide (Al₂O₃) nanoparticles. Simulations explored weight fractions from 0–2%, focusing on droplet velocity and size distribution. Results show increasing nanoparticle content significantly enhances atomization. For FT fuel, maximum droplet velocity reduced from approximately 28.0 m/s to 26.9 m/s with 2.0 wt% aluminum oxide nanoparticles. Concurrently, maximum droplet diameter decreased from 1.30 × 10⁻⁴ m to 9.1 × 10⁻⁵ m with Al nanoparticles and to 7.7 × 10⁻⁵ m with Al₂O₃ nanoparticles at 2.0 wt% loading. Similar trends were observed for RP-3 fuel, where both velocity and droplet size decreased with increasing nanoparticle concentration. These findings underscore the potential of nanoparticle-mixed fuels to improve spray quality, critical for combustion efficiency in advanced propulsion and energy systems. The numerical model demonstrated strong agreement with available reference data, validating its predictive capability for complex nanofluid spray dynamics.